Many electrical switches are of the type which encounter "overtravel" after the state of the electrical connection of the switch has been altered. In most instances, an actuator is employed to operate the switch. The actuator and its associated components usually go through a "pretravel" before electrical connection is made or the switch state is altered, which sometimes is termed the "operating point". The actuator and/or its associated components go through an overtravel condition of movement after the operating point. Upon release of the actuator, reverse movement usually takes place and a "release point" occurs when the electrical connection and its associated circuit is transferred back to its original state. This usually occurs sometime during return movement of the actuator.
In some instances, such as shown in U.S. Pat. No. 4,778,960 to James Blair, dated Oct. 18, 1988 and assigned to the assignee of this invention, a floating, operating and release point switch is disclosed. This concept allows the switch to utilize a movement differential to actuate or deactuate a circuit rather than cause actuation or deactuation at respective absolute positions. In this patent, a switch actuator includes a base and a plunger mounted for movement in the base. A friction piece surrounds the plunger and normally frictionally grasps the plunger so as to be movable therewith and relatively movable with respect to the plunger when movement of the friction piece is resisted, as by engagement with switch contacts. The plunger, therefore, overtravels the friction piece once contact is made. On return movement of the plunger, the friction piece again frictionally grasps the plunger and moves away from the switch contacts. In other words, conjoint and relative movement between the plunger and the friction piece in this switch actuator relies upon maintaining a friction surface between the plunger and the friction piece.
In copending U.S. application Ser. No. 243,506, filed Sept. 8, 1988, and assigned to the assignee of the present invention, an improved switch actuator is shown wherein a plunger is mounted on a base for movement relative thereto to establish an electrical connection. Actuator means are operatively associated with the plunger and include wedge means between the plunger and an actuator member. Such a structural combination accommodates manufacturing tolerances and compensates for wear during use. However, the switch actuator again relies upon frictional surfaces to provide conjoint and relative movement between the plunger and the switch actuating means.
This invention is directed to further improvements in such switch actuators and substantially eliminates any wear problems by eliminating total reliance on maintaining frictional surfaces by providing a spring loading between the actuating member and the plunger, with spring bias forces facilitating conjoint and relative movement therebetween. The actuator is very compact and has few parts.